The present invention relates to improved non-clogging and wear-reducing screen assemblies for a vibrating screening machine.
By way of background, in U.S. Pat. No. 4,033,865 a screen assembly for a vibrating screening machine is disclosed which consists of a pair of superimposed contiguous abutting screens mounted in a frame for the prevention of clogging or blinding. However, when the superimposed screens were mounted in their operative positions in the vibrating screening machine, large spans of screens were unsupported. If high accelerations were applied to the screen assembly, the upper screen wore rapidly because the large amplitude of movements of its large unsupported span produced excessive abrasion with the material being screened, and thus the useful screen life was reduced. Therefore, to avoid this, the acceleration forces were reduced with a corresponding reduction in productivity.